The present invention relates to an improvement in a ferrule for use in an optical connector, used to connect optical fibers to each other or connect an optical fiber and light-receiving or -emitting element to each other.
Ordinarily, as illustrated in FIG. 8, a ferrule for use in an optical connector is constructed in such a way that an exposed forward end optical fiber 101A of an optical fiber cable 101 is fixed in an insertion hole 100A in the axial direction of a ferrule main body 100 shaped like a circular-columnar body by using an adhesive. As illustrated in FIG. 9, two ferrules for use in an optical connector each having this construction are axially aligned with and connected to each other by using a circular-cylindrical sleeve 103. That is, the two ferrules are inserted, by being slid, into the circular-cylindrical sleeve 103 axially formed with a split (not illustrated), whereby the mating ferrules are caused to oppose each other at a central portion of the sleeve and are connected to each other.
Accordingly, when mating ferrules for use in an optical connector are repeatedly attached and detached within the sleeve, waste generated due to the friction between the ferrule main body and the sleeve, dust suspended in the air, etc. attach onto an outer-peripheral surface 102 or forward end surface 103 of the ferrule main body. As a result, there arises the inconvenience that axial displacement occurs between the two ferrules to be connected together or waste enters between connection end surfaces of the two ferrules and as a result a clearance is produced therebetween to result in a defective contact between the two. As a consequence, as illustrated in FIG. 10, with the repeated attachment/detachments of the ferrules, the optical transmission loss made between the two increases. In consequence, for example, there is a problem in that the insertion loss tended to rapidly increase after a repeated approximately 100-time use of the optical connector.
Accordingly, an object of the present invention is to provide a ferrule for use in an optical connector enabling effective suppression of the increase in the insertion loss due to repeated attachments/detachments of the optical connector.
The present invention provides a ferrule for use in an optical connector, the ferrule comprising a main body of the ferrule fitted into a connection sleeve and having an optical fiber fixed therein, in which a plurality of grooves are formed in an outer-peripheral surface of the ferrule main body including a fitting surface thereof located between the ferrule main body and the connection sleeve. According to this construction, in cases where dust has attached for various reasons onto the fitting surface between the ferrule main body and the connection sleeve, when the ferrule for use in an optical connector is fitted into the connection sleeve, at the fitting time the dust on the fitting surface is caused to drop into the groove formed in the fitting surface. This makes it possible to maintain the fitting surface of the ferrule main body and the fitting inner-peripheral surface of the connection sleeve in a required fitted state.
Also, the present invention provides a ferrule for use in an optical connector, comprising a main body of the ferrule having formed therein an insertion hole having inserted and fixed therein an optical fiber, in which a plurality of concentric annular grooves are formed in a connection end surface of the ferrule main body having a connection end of the optical fiber exposed thereon. According to this construction, when the ferrule main body abuts within a connection sleeve on a connection end surface of the other ferrule, the dust having attached for various reasons onto the connection end surfaces is caused to drop into the annular grooves formed therein. This makes it possible to maintain the connection end surfaces of the two ferrules in a required contact state.